Scientists have developed a technique that can determine the 3D position of individual atoms with one single image, using a special type of microscope.
For more than a decade, physicists have been able to accurately measure the location of individual atoms to a precision smaller than one-thousandth of a millimeter using a special type of microscope called quantum gas microscopy. However, this method has so far only provided the x and y coordinates of an atom. Information on the vertical position of the atom, i.e., the distance between the atom and the microscope objective, is lacking. A new method has now been developed that can determine all three spatial coordinates of an atom with one single image. This method – developed by the University of Bonn and University of Bristol – is based on an ingenious physical principle .
Principle
The new method uses an effect that has been known in theory since the 1990s but had not yet been used in a quantum gas microscope. The effect is called spin-orbit coupling and it describes how the spin of an atom interacts with its orbital motion. In simple terms, spin-orbit coupling causes the atom to rotate around its own axis depending on its direction of motion. This rotation affects how the atom emits light when it is exposed to a laser beam, which stimulates it to fluoresce. The resulting fluorescence shows up in the quantum gas microscope as a slightly blurred, round speck.
However, if the laser beam is polarized in a certain way, the round speck turns into a dumbbell-shaped speck. The orientation of the dumbbell depends on the direction of rotation of the atom, which in turn depends on its z coordinate. By analyzing the shape and orientation of the dumbbell, it is possible to infer the vertical position of the atom with one single image.
Applications
The new method has several advantages over the conventional method of measuring the z coordinate of an atom. It is faster, simpler and more precise. It also allows for measuring the 3D position of multiple atoms simultaneously, which is useful for studying quantum many-body systems and quantum simulations. The researchers hope that their technique will open up new possibilities for exploring quantum phenomena at the atomic level.
Conclusion
Scientists from the University of Bonn and University of Bristol have developed a new method that can measure the 3D position of individual atoms with one single image using a quantum gas microscope. The method relies on an effect called spin-orbit coupling, which causes the atom to rotate around its own axis depending on its direction of motion. This rotation affects how the atom emits light when it is stimulated by a laser beam, which results in a dumbbell-shaped speck in the microscope image. The shape and orientation of the dumbbell reveal the vertical position of the atom. The new method is faster, simpler and more precise than the conventional method and has potential applications for studying quantum many-body systems and quantum simulations.
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